If there's an "in house sound" then it comes by design and by doing something/altering/colouring/boosting the signal passing through the amp. That could be something as simple as boosting bass or treble frequencies. Any amp manufacturer that deliberately sets out to do this cannot claim to be making a High Fidelity product as by definition, they are altering the fidelity of the signal. Now some people may prefer the resulting sound and I've no issue with that but it can't be claimed to be Hi-Fi.
Beyond that scenario, all Hi-Fi amps running within their design parameters and not distorting or clipping should sound pretty similar assuming you're not putting too heavy a load on them speaker wise.
If there's an "in house sound" then it comes by design and by doing something/altering/colouring/boosting the signal passing through the amp. That could be something as simple as boosting bass or treble frequencies. Any amp manufacturer that deliberately sets out to do this cannot claim to be making a High Fidelity product as by definition, they are altering the fidelity of the signal. Now some people may prefer the resulting sound and I've no issue with that but it can't be claimed to be Hi-Fi.
Beyond that scenario, all Hi-Fi amps running within their design parameters and not distorting or clipping should sound pretty similar assuming you're not putting too heavy a load on them speaker wise.
There is no agreed upon standard for Hi Fi and all attempts to introduce one have been vigorously resisted.
Yes, with theoretical design practices adhered too all amps not overdriven " should" sound similar, but no one is doing this, in fact , in these days of custom Asics and house tuning no one is even using the same parts for any class of amplifier design.
Basically , you would be hard pressed to find any two amps from any two major manufacturers that sound the same these days. Almost all have some kind of signature sound.
My point is if you, as a manufacturer, deliberately set out to boost a part of the signal then you can't call it HiFi. There are some amps that measure flat across the audible range and it's not beyond difficult to do in this day and age.
Who are the people resisting standards for High Fidelity anyway? Work that out and you may deduce their motives.
But you can call it Hi Fi, thats my point. You can call anything you want Hi Fi because there is no official standard and no definition of that that term to be measured against.
Every " Hi fi" manufacturer resists a standard because it limits what they can market or sell.
I agree that the response should be flat across the audible range, thats what "should" be a feature of a good system and thats what i always look for, but until that becomes a standard then its effectively just idealism.
These days there are known and very popular companies that go out of their way to avoid a flat response and call it a signature sound. Beats for example have a 6db boost across the lower end... They sell as a premium brand.
Not everyone is as extreme as that, but this is the problem in the audio industry these days. Marketing and Hype determine what sells, not performance, and as such, hardly anyone is aiming for what "should" be the best performance, instead they sell awful products with high value and "hip" trademarks.
It would seem that having the correct logo on show is what sells.
If there was a standard whereby reviewers could say, "this is what should be happening and this unit is failing miserably", then half of these companies would be gone.
They all know this of course, which is why they all resist it so much, they could no longer throw together cheap nasty materials in an underperforming unit, stick it in a fancy cardboard box and market it as a premium product.
I think there will always be an, "in house sound",because to a certain extent, making great hi fi is an artists job, as well as a technicians.
Because human ears are not measuring instruments, our perception of hi fi is different for everybody, because we bring ourselves to the experience. Hi fi could be made perfect on paper as noiseboy72 pointed out, but sounds terrible to the ear,. This where the expertise comes in, to paint enough warmth onto the soundstage, that tinges the cold clarity with an image we can recognise, that's the trick of it.